Communication system for maintaining cells in an energy saving state based on access restrictions

Abstract

A communication system capable of preventing unnecessary switching of an energy saving cell between a normal operation state and an energy saving state. An energy saving cell (ES cell) is in a dormant state that is the energy saving state. In this case, when being notified of a wake-up request message from a communication terminal device (UE), the ES cell executes access restriction control to judge whether the UE can access its own cell. If judging that the UE can access its own cell, the ES cell switches on its own cell and shifts from the dormant state to an active state that is the normal operation state.

The invention claimed is: 
     
       1. A communication system comprising:
 a communication terminal device; and 
 a base station device that configures at least one cell capable of radio communication with said communication terminal device, 
 wherein 
 said at least one cell comprises an energy saving cell switchable between a normal operation state and an energy saving state in which power consumption is lower than in said normal operation state, and 
 when said energy saving cell is in said energy saving state, access restriction control is executed to judge whether said communication terminal device is allowed to access said energy saving cell, 
 when it is judged that said communication terminal device is allowed to access said energy saving cell by said access restriction control, a wake-up process of shifting said energy saving cell from said energy saving state to said normal operation state is performed, and 
 when it is judged that said communication terminal device is not allowed to access said energy saving cell by said access restriction control, the energy saving cell sends the communication terminal device a rejection message and the energy saving cell remains in the energy saving state. 
 
     
     
       2. The communication system according to  claim 1 , wherein said access restriction control is executed by said energy saving cell. 
     
     
       3. The communication system according to  claim 1 , wherein
 said at least one cell comprises a serving cell connected with said communication terminal device, and 
 said access restriction control is executed by said serving cell. 
 
     
     
       4. The communication system according to  claim 1 , wherein said access restriction control is executed by said communication terminal device. 
     
     
       5. The communication system according to  claim 1 , further comprising a higher-layer device located at a layer higher than that of said base station device,
 wherein said access restriction control is executed by said higher-layer device. 
 
     
     
       6. The communication system according to  claim 1 , wherein said access restriction control is executed based on restriction information provided for said communication terminal device to restrict access of its own device to said at least one cell. 
     
     
       7. The communication system according to  claim 1 , wherein
 said at least one cell comprises a cell for specific subscribers which allows access to predetermined subscribers, and 
 said access restriction control is executed based on information about said cell for specific subscribers. 
 
     
     
       8. The communication system according to  claim 1 , wherein the energy saving cell sends the rejection message to the communication terminal device via a serving cell of the communication terminal device.